1st off, you are not as bad as you think.
In order of importance, you do need to change your approach slightly, IMHO. I just got done not too long ago with a Portugal game, so I'm still a bit tuned into how to proceed.
1. Research: You have your research sliders (budget window) set for roughly even division of monthly income into each category. Don't do it this way. While certainly more historically accurate, it prevents you from maximizing long-term income. At early parts of the game, it isn't as relevant to be up to par militarily with the AI nations, because you can usually out-manoeuver them in a war anyway. So most people here will stick as much of their monthly income into Infrastructure research, at least until you have reached level 5. This is the magic level at which you can start to promote mayors to governors, which allows you to divert monthly income into your treasury with a lessened impact upon inflation.
So, a methodology for research for Portugal might be: all available money into researching infrastructure until you reach level 2 (whereupon you build fine arts academies to accelerate the pace of increasing stability, soon to be a difficult chore as you grow bigger), then if need be spend briefly on land technology to get to level 5 (assaults, very helpful in dealing with native cities), then infrastructure to level 3 (allows breweries, which then help your trade research without you having to divert monthly income), perhaps even to level 4 if you can get away with it, back to land to get to level 9 (which gives you a new Combat Resolution Table), then back to infra through level 5. At that point, you can work on Trade, with again occaisional focus on either land or naval to achieve important level bonuses. Keep in mind that the more you lag behind other nations in land or naval, the more that lag contributes in "neighbor bonus" monthly to researching that technology! Some of the small Catholic nations sprint out to a big lead in those areas, so you get some dramatic help without spending one gold ducat of your own.
2. Taxes: You don't have a tax collector in Tangiers. This deprives you of Census Taxes every year from that province. It also deprives you of 1d per year in production income from that province. As a general rule of thumb, if you capture a city and are ceded the province in a peace resolution, immediately promote the tax collector, regardless the revolt risk.
3. You aren't colonizing nearly fast enough, nor in the areas you need to. Portugal currently in your game has 4 explorers and 4 conquistadors. With those, you should be all the way around the horn of Africa, and you should be master of the whole of Eastern South America. In addition, your conquistadors should be aware by now of all Brazillian and Argentinian provinces, and you should also have all the Eastern North American provinces discovered, at least to the borders of the various indian nations. The supply of explorers and conquistadors is not endless, so you have to make hay with them while you can. Keep in mind that the conquistador only has to be in the province when you
send a settler for the bonus to chances of success; once you click send, the fate of the settler is already determined and the conquistador can head to the next province.
I do not think Portugal ever should worry about the consequences of the Treaty of Tordesillas (probably hasn't even been put into effect yet in your game). This Treaty will eventually allow Portugal and Spain to march troops into provinces in their colonial spheres owned by Catholic nations
without declaring war, and take over ownership. Thus, if Portugal settles Tocuvo, as you have done, once the ToT is in effect (early 1500's), Spain can send troops in and claim it as Spain's, without Spain declaring war on Portugal. If you have a city there already, with a fortress, Spain has to siege it successfully, otherwise, the province immediately changes ownership. If Portugal wants it back, it has to declare war on Spain. The reverse is true in Portugal's areas (Brazil, Africa, India, and the Far East), but an AI Spain won't colonize them anyway.
Why then should Portugal not worry? Because all Portugal need do is ally with Spain. I have never had an allied Spain take a ToT colony from me as Portugal. The only downside to this is that you can't then fight Spain in an attempt to conquer it, but from the looks of things, you didn't plan that anyway. Ally Spain, then beat them to all the colonies you can, crippling Spain for the remainder of the game.
(Hint: set your in game pop-ups to pause and pop-up whenever a new province is discovered by anyone; it gets annoying, but it is a sure fire method for knowing when Spain has found a new province, whereupon you simply send a settler there at once if you already discovered it yourself.
)
If you wish to worry about the ToT, then you still have plenty of areas to settle. All of Brazil. All of the eventual United States, with the exception only of Florida and the Gulf Coast. All of Africa, including the VERY important and VERY strategic location of Table in South Africa. All of the Far East (except the Philippines), and All of India. Keeps you busy.
4. Trading Posts v. Colonies: You have some trading posts that you are advancing to higher level trading posts which you really should be turning into colonies and, eventually, cities. Massachussets is the prime example. It trades in fish, a medium value item, and has a high potential tax value (5) when turned into a city. So rather than make it a level 6 TP, you want to make it a colony, then turn it into a city. It can then recruit troops, it will pay taxes as well as production income and trade taxes. It isn't adding much to the value of Tago's Center of Trade, so don't continue to make it a higher level trading post.
In general, make provinces with high value trade items (sugar, wine, spice, chinaware, cloth, copper and iron, salt) trading posts, unless you need a strategic spot for your ships to put to port to cancel out accumulated naval attrition. Thus, many people make Recife a colony, so that you have a place to put to port on the SA coast after crossing the Atlantic. Make low value item provinces colonies, focussing first on those with a high potential tax value. Medium value provinces are best taken by TP's until you have the time and money to aggressively colonize.
5. Trade, Trade, Trade: Portugal starts with the third highest Trade efficiency in the game. From the get go, you must flood CoT's with your merchants. Tago, France, Flanders and Mecklemburg should be loaded with five Portugese merchants apiece, and you cannot let the Tago CoT be less than five ever if you can help it, since all your own provinces are likely trading there. You seem to be doing well there, so all I can say is, keep it up.
In short, 1: research infrastructure virtually exclusively until you get to level 5; 2: promote tax collectors in Tangiers and any colony you manage to grow into a city; 3: make really strong use of your explorers and conquistadors and colonize all the areas you can (Spanish Ally?); 4: change some of the TP's into colonies, and get a city or two in the new world, so you can recruit troops to take on paga nations later; 5: Trade.
Good luck with Portugal.
